Impact drive type actuator

ABSTRACT

An impact drive type actuator ( 10 ) is comprised of a wire-shaped shape memory alloy ( 11 ) which contracts upon being electrified and heated, a disk-shaped insulating heat conductor ( 12 ) which contacts this wire-shaped shape memory alloy ( 11 ) and releases the heat which is generated at the wire-shaped shape memory alloy, and a drive circuit ( 16, 17 ) which instantaneously electrifies the wire-shaped shape memory alloy and instantaneously makes the wire-shaped shape memory alloy contract. According to this impact drive type actuator, it realizes a heat conduction structure which gives rise to a high heat dispersion action by the heat characteristics of the shape memory alloy, so it becomes possible to utilize the deformation by extension and contraction of a shape memory alloy which has a wire-shaped form, improve the speed and response of the deformation operation characteristics, and improve practicality.

RELATED APPLICATIONS

This application is a U.S. national phase application of InternationalApplication Number PCT/JP2011/068769 filed Aug. 19, 2011 claimingpriority of Japanese Application Number 2010-185151 filed Aug. 20, 2010.

TECHNICAL FIELD

The present invention relates to an impact drive type actuator, moreparticularly relates to an impact drive type actuator which utilizes thechange by extension and contraction in the length direction of a shapememory alloy which has a wire-shaped form so as to enable an impact-likemotion (impact operation) in a horizontal direction (or planardirection) or a vertical direction (front-back direction or thicknessdirection) and a rotational operation or linear operation based onrepetition of the impact operation.

BACKGROUND ART

As an actuator which utilizes a shape memory alloy, in the past therehave been the actuators which are described in the Patent Literatures 1to 3.

The Patent Literature 1 proposes a technique for designing a shapememory alloy actuator which has a two-way shape memory effect whichenables the shape memory alloy actuator to withstand repeated operationa very large number of times, be strikingly lengthened in operatinglifetime, be broadened in range of operation, and further be stabilizedin shape. The “two-way shape memory effect” is the phenomenon whereby ifdeforming a shape memory alloy which memorizes a certain shape at a lowtemperature, then heating it, the alloy returns to its originalmemorized shape and, furthermore, if making it low in temperature, thealloy returns to the shape deformed to at the low temperature. With thetwo-way shape memory effect, by just heating and cooling, the shapememory alloy independently repeatedly changes in shape without requiringaction of a bias force from the outside. In a shape memory alloyactuator which has a two-way shape memory effect, behavior storing twoshapes—the shape deformed to at the time of a low temperature (shape inmartensite state) and the shape returned to at the time of a hightemperature (shape in matrix phase state)—is exhibited.

In a shape memory alloy actuator which is described in the PatentLiterature 2, a plurality of shape memory alloy wires are arrangedbetween a support member and a moving member—both flat plates in shape.These shape memory alloy wires are laid so as to contact mating partsformed at facing surfaces of the support member and moving member and,furthermore, so as to bridge them in a loose manner. The moving memberis given external force from the outside to be pushed against thesupport member. The shape memory alloy wires are in a loose state atordinary temperature. When electrified and heated, they contract totense up and are extended straight whereby the moving member is moved.

In a drive device which is disclosed in the Patent Literature 3, thereis provided an actuator which has a shape memory alloy wherein the speedof response is raised. In this actuator, the shape memory alloy issupplied with a drive current and made to generate heat to cause areturn operation. Furthermore, control is performed to generate anamount of drive current for the shape memory alloy so as to give anamount of displacement of the shape memory alloy based on a target valueof displacement of the moving member. The invention which is disclosedin the Patent Literature 3 is therefore a drive device which isconstituted by an actuator which has a shape memory alloy whichefficiently increases the speed of response of the actuator.

PRIOR ART LITERATURE Patent Literature

-   Patent Literature 1: Japanese Patent Publication No. 2003-003948 A1-   Patent Literature 2: Japanese Patent Publication No. 2005-226456 A1-   Patent Literature 3: Japanese Patent Publication No. 2006-166555 A1

SUMMARY OF INVENTION Technical Problems

An actuator which utilizes a shape memory alloy performs a driveoperation by utilizing the behavior of a shape memory alloy ofmemorizing a change in shape between a shape which it deforms to at thetime of a low temperature (at the time of ordinary temperature) and ashape which it recovers to at the time of a high temperature (at thetime of being electrified and generating heat). The response of thebehavior of the shape memory alloy depends on the change in the heatstate from the time of a high temperature to the time of a lowtemperature. An actuator which utilizes a conventional shape memoryalloy does not sufficiently consider the change in the heat state fromthe time of a high temperature to the time of a low temperature, so hadthe defects of a low response in operation and a low practicality.

An object of the present invention, in consideration of the problem, isto provide an impact drive type actuator which considers the heatcharacteristics of a shape memory alloy and realizes a heat conductionstructure giving rise to a high heat dispersion action so as to utilizeextension and contraction deformation of a shape memory alloy which hasa wire-shaped form, improve the speed and response of the deformationoperation characteristics, and improve the practicality.

Solution to Problem

The impact drive type actuator according to the present invention isconstituted as follows to achieve the object.

The impact drive type actuator according to the present invention ischaracterized by being provided with a wire-shaped shape memory alloywhich contracts upon being electrified and heated, an insulating heatconductor which contacts the wire-shaped shape memory alloy and releasesthe heat which is generated at the wire-shaped shape memory alloy, and adrive circuit which instantaneously electrifies the wire-shaped shapememory alloy to make the wire-shaped shape memory alloy contract.

In the impact drive type actuator, the wire-shaped shape memory alloywhich is arranged in a predetermined laid out state is provided with aninsulating heat conductor which is made to contact the wire-shaped shapememory alloy so as to quickly disperse and release the heat which wasgenerated at the shape memory alloy, so it is possible to quicklyrelease the heat which was generated by heat emission due to theinstantaneous electrification and possible to quickly lower thetemperature of the wire-shaped shape memory alloy.

In the above constitution, preferably the insulating heat conductor atleast partially has a substantially circumferential shape, thewire-shaped shape memory alloy is arranged so as to contact thecircumferential surface of the insulating heat conductor, and thewire-shaped shape memory alloy makes the insulating heat conductordisplace in position when electrified and contracts.

The heat which is generated at the wire-shaped shape memory alloy at thetime of electrification is dispersed by utilizing the entire area of asubstantially half circle part of the circumferential surface of theinsulating heat conductor, so the path for release of heat can beenlarged and the wire-shaped shape memory alloy can quickly drop intemperature. Further, by utilization in a half circle shape and byhaving the wire-shaped shape memory alloy as a whole abut against thehalf circle part of the circumferential surface of the insulating heatconductor, the contraction operation of the wire-shaped shape memoryalloy can be converted into movement of the insulating heat conductor inthe radial direction and as a drive part which enables impact in theradial direction use of the insulating heat conductor is possible.

In the above constitution, preferably the circumferential surface of theinsulating heat conductor is formed with a groove, and the wire-shapedshape memory alloy is arranged in the groove. The groove is, forexample, one with a V-shaped cross-section. The wire-shaped shape memoryalloy is arranged so as to contact the two wall surfaces of the V-shapedgroove, so the heat dispersion function can be improved.

In the above constitution, preferably the insulating heat conductor iscomprised of two component members which face each other substantiallyin parallel and have pluralities of mating projecting parts, thewire-shaped shape memory alloy is arranged between the two componentmembers so as to contact the mating projecting parts, and thewire-shaped shape memory alloy changes an interval between the twocomponent members when it is electrified and contracts. According tothis constitution, the contraction operation of the wire-shaped shapememory alloy can be converted to movement (displacement) of platemembers in a direction perpendicular to the surfaces of the platemembers and the interval between the two component members can bechanged.

In the above constitution, preferably the insulating heat conductor iscomprised of two component members which face each other substantiallyin parallel and have substantially rod shapes or pipe shapes, thewire-shaped shape memory alloy is spirally wound around the twocomponent members to contact their circumference, and the wire-shapedshape memory alloy makes the two component members displace so as toreduce the interval between them when it is electrified and contracts.

The two component members of the insulating heat conductor are arrangedat a distance from each other. The distance is maintained by having onecomponent member elastically supported. One is f fixed in place and theelastically supported other is made movable. In this state, thewire-shaped shape memory alloy is made to contract whereby the othercomponent member is displaced to approach the one fixed componentmember.

In the above constitution, preferably the wire-shaped shape memory alloyis wound in a ring shape or a figure eight shape. In a constitutionwhere it is wound in a figure eight shape, it is possible to increasethe contact area between the wire-shaped shape memory alloy and thesurface of the rod-shaped insulating heat conductors and thereforepossible to improve the ability to disperse the heat generated byelectrification.

In the above constitution, preferably the two component members of theinsulating heat conductor are respectively comprised so that at leastthe outer surfaces which contact the wire-shaped shape memory alloy arecurved so that their cross-sections include substantially half circles.

In the above constitution, preferably the insulating heat conductor isformed as a rotor which is provided freely rotatably, the wire-shapedshape memory alloy is provided contacting and winding around thecircumferential surface of the insulating heat conductor and is fastenedat its two ends, and the wire-shaped shape memory alloy tightens againstthe insulating heat conductor and brakes its rotational operation whenit is electrified and contracts. In the above constitution, thecontraction action of the wire-shaped shape memory alloy can be utilizedas means for braking rotational operation of the rotor.

In the above constitution, preferably the insulating heat conductor isformed as a rotor which is provided freely rotatably, itscircumferential surface being formed with a spiral shaped groove, thewire-shaped shape memory alloy is provided contacting the inside of thegroove and winding around the circumferential surface of the insulatingheat conductor, one end being fixed and the other end being supported byan elastic mechanism to be tensed, and the wire-shaped shape memoryalloy makes the insulating heat conductor rotate when it is electrifiedand contracts.

In the above constitution, use is possible as an impact drive typeactuator which repeatedly makes the wire-shaped shape memory alloycontract in a short time and utilizes the engagement relationship withthe spiral shaped groove which is formed at the circumferential surfaceof the rotor insulating heat conductor so as to make the rotorinsulating heat conductor turn in any direction.

In the above constitution, preferably, separate from the wire-shapedshape memory alloy, a second wire-shaped shape memory alloy is provided,the second wire-shaped shape memory alloy is provided contacting theinside of the groove at the circumferential surface of the insulatingheat conductor and winding in a direction opposite to the windingdirection of the wire-shaped shape memory alloy, one end being fixed andthe other end being supported by a second elastic mechanism to betensed, and the wire-shaped shape memory alloy makes the insulating heatconductor turn in one direction when it is electrified and contractswhile the second wire-shaped shape memory alloy makes the insulatingheat conductor turn in the opposite direction when it is electrified andcontracts.

In the above constitution, by utilizing two wire-shaped shape memoryalloys, rotation in two direct ions—the clockwise direction andcounterclockwise direction—becomes possible.

In the above constitution, preferably the groove which is formed at thecircumferential surface of the insulating heat conductor is a spiralshaped thread groove, and this thread groove is structured so that thewire-shaped shape memory alloy does not contact itself.

In the above constitution, preferably the insulating heat conductor hasa plate-shaped form, two plate-shaped insulating heat conductors arearranged facing each other, one plate-shaped insulating heat conductorbeing fixed in place, the other plate-shaped insulating heat conductorbeing arranged to be freely movable and being provided to be pulled inone direction by an elastic mechanism, the wire-shaped shape memoryalloy is arranged between the two plate-shaped insulating heatconductors so that the wire-shaped shape memory alloy connects the twoplate-shaped insulating heat conductors, and the wire-shaped shapememory alloy makes the freely movable plate-shaped insulating heatconductor displace by exactly a predetermined distance against theelastic mechanism when it is electrified and contracts.

In the above constitution, preferably a moving member is arranged on topof the freely movable plate-shaped insulating heat conductor in afriction contact state and the freely movable plate-shaped insulatingheat conductor is repeatedly made to displace whereby the moving memberis made to move in one direction.

In the above constitution, preferably the drive circuit is comprised ofa booster circuit which converts input voltage to a high voltage, acapacitor which is charged by that output voltage, and a switchingdevice which is connected in series with the wire-shaped shape memoryalloy from said capacitor and instantaneously runs current to thewire-shaped shape memory alloy.

In the above constitution, preferably the insulating heat conductor isconstituted by aluminum oxide (alumina) or aluminum nitride at least atthe surface part which contacts the wire-shaped shape memory alloy.

Furthermore, in the above constitution, preferably the insulating heatconductor is comprised of two component members which face each othersubstantially in parallel and which are provided with pluralities ofprojecting members, at each of the two component members, the pluralityof projecting members are separated, the plurality of projecting membersare comprised of conductive members, and between the two componentmembers, the wire-shaped shape memory alloy is arranged so as to contactparts comprised of the conductive members of the projecting members, andthe wire-shaped shape memory alloy changes the interval of the twocomponent members when it is electrified and contracts.

Advantageous Effects of Invention

According to the impact drive type actuator according to the presentinvention, a wire-shaped shape memory alloy which is arranged in apredetermined laid out state is provided with various shapes ofinsulating heat conductors in a manner enabling as much effectivecontact as possible. Due to these insulating heat conductors, heat whichwas generated at the wire-shaped shape memory alloy due to thepulse-like electrification is quickly dispersed and released, so thewire-shaped shape memory alloy can be quickly lowered in temperature,instantaneous operation able to be repeated in a relatively short timecan be realized, and a highly practical impact drive type actuator canbe achieved.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] This is a perspective view which shows the appearance ofprincipal parts of an impact drive type actuator according to a firstembodiment of the present invention.

[FIG. 2] This gives plan views which show a state (A) of the impactdrive type actuator according to the first embodiment when thewire-shaped shape memory alloy is at a low temperature and a state (B)where it is electrified and heated (high temperature).

[FIG. 3] This is a partial cross-sectional view which shows a state ofcontact of a wire-shaped shape memory alloy and a disk-shaped insulatingheat conductor in the impact drive type actuator according to the firstembodiment.

[FIG. 4] This is a partial cross-sectional view which shows a state ofheat dispersion through contact of the wire-shaped shape memory alloyand the disk-shaped insulating heat conductor in the impact drive typeactuator according to the first embodiment.

[FIG. 5] This is a perspective view which shows the appearance ofprincipal parts of an impact drive type actuator according to a secondembodiment of the present invention.

[FIG. 6] This gives end views which show a state (A) of the impact drivetype actuator according to the second embodiment when the wire-shapedshape memory alloy is at a low temperature and a state (B) where it iselectrified and heated (high temperature).

[FIG. 7] This is a perspective view which shows the appearance ofprincipal parts of an impact drive type actuator according to a thirdembodiment of the present invention.

[FIG. 8] This gives plan views which show a state (A) of the impactdrive type actuator according to the third embodiment when thewire-shaped shape memory alloy is at a low temperature and a state (B)where it is electrified and heated (high temperature).

[FIG. 9] This is a view of an impact drive type actuator according to afirst modification of the third embodiment and similar to (A) of FIG. 8.

[FIG. 10] This is a partial perspective view of impact drive typeactuator according to a second modification of the third embodiment andshows a direction of winding of the wire-shaped shape memory alloy.

[FIG. 11] This gives plan views which show a state (A) of the impactdrive type actuator according to the second modification of the thirdembodiment when the wire-shaped shape memory alloy is at a lowtemperature and a state (B) where it is electrified and heated (hightemperature).

[FIG. 12] This is a perspective view which shows the appearance ofprincipal parts of an impact drive type actuator according to a fourthembodiment of the present invention.

[FIG. 13] This is a perspective view which shows the appearance ofprincipal parts of an impact drive type actuator according to a fifthembodiment of the present invention.

[FIG. 14] This is a waveform diagram which shows a drive current whichis supplied to an impact drive type actuator according to the fifthembodiment.

[FIG. 15] This is a perspective view which shows the appearance ofprincipal parts of an impact drive type actuator according to a sixthembodiment of the present invention.

[FIG. 16] This gives views for explaining a drive state (A) of a rotaryoperation in a counterclockwise direction by the operationcharacteristics of the impact drive type actuator of the sixthembodiment and a drive state (B) of a rotary operation in a clockwisedirection.

[FIG. 17] This is a partial cross-sectional view which shows anengagement relationship of the wire-shaped shape memory alloy and athread part of an outer circumferential surface of a rotor insulatingheat conductor in the impact drive type actuator of the sixthembodiment.

[FIG. 18] This is a perspective view which shows the appearance ofprincipal parts of an impact drive type actuator according to a seventhembodiment of the present invention.

[FIG. 19] This is a partial cross-sectional view which shows arelationship of two plate-shaped insulating heat conductors and awire-shaped shape memory alloy in the impact drive type actuatoraccording to the seventh embodiment.

[FIG. 20] This is a perspective view which shows the appearance ofprincipal parts of an impact drive type actuator according to an eighthembodiment of the present invention.

[FIG. 21] This gives views which explain a linear drive operation by animpact drive type actuator according to the eighth embodiment.

[FIG. 22] This is a diagram of an electrical circuit which is used inthe impact drive type actuator according to the present invention.

[FIG. 23] This is a waveform diagram which shows the operations of theparts of the drive circuit.

DESCRIPTION OF EMBODIMENTS

Below, preferred embodiments (examples) of the present invention will beexplained with reference to the drawings.

First Embodiment

Referring to FIG. 1 to FIG. 4, a first embodiment of an impact drivetype actuator according to the present invention will be explained. Inthe figures, 10 indicates an impact drive type actuator, 11 awire-shaped shape memory alloy, and 12 an insulating heat conductorwhich has a disk shape (below, referred to as a “disk-shaped insulatingheat conductor 12”). The wire-shaped shape memory alloy 11 has apredetermined length which is required for forming the impact drive typeactuator 10. In practice, the wire-shaped shape memory alloy 11 may haveany wire size and wire length. These are suitably determined inaccordance with the size of the impact drive type actuator 10 as a wholebeing prepared. Further, the disk-shaped insulating heat conductor 12 istypically formed by aluminum oxide (alumina) and preferably has a highelectrical insulating property and heat conductivity. Note that thedisk-shaped insulating heat conductor 12 may have as little as thesurface part which contacts the wire-shaped shape memory alloy 11 madeof aluminum oxide. In this case, for example, the disk-shaped insulatingheat conductor 12 as a whole is made of aluminum and just the requiredsurface part is changed to aluminum oxide. The aluminum oxide surface isformed by a process similar to electroplating, that is, anodicoxidation, but is much harder than the original aluminum so has thepreferable properties of an increased surface hardness and improved wearresistance. Further, as the material of the disk-shaped insulating heatconductor 12, aluminum nitride or diamond may also be used. Aluminumnitride or diamond is better in heat conductivity than aluminum oxideand, if ignoring the cost, is a more suitable material.

Furthermore, regarding the term “insulating heat conductor”, this memberis generally made of a conductive material. To impart an insulatingproperty, it is also possible to split the conductive material intoseveral sections and perform treatment or processing to secure aninsulating property seen overall.

The disk-shaped insulating heat conductor 12 is, for example, providedon a base member 13 and, as shown in FIG. 1 etc., is attached by astructure enabling the contraction action of the wire-shaped shapememory alloy 11 to cause it to move in the direction of the arrow AL1(any linear direction in plane). The disk-shaped insulating heatconductor 12 is supported by an elastic mechanism 14 so as to be pressedin a direction opposite to the arrow AL1. The elastic mechanism 14 isconstituted by an end part 14 a which is fastened to the base member 13,an end part 14 b which contacts one location of the circumferentialsurface of the disk-shaped insulating heat conductor 12 and is able tomove to push that location, and a coil spring member 14 c which isarranged between the two ends 14 a, 14 b and is provided in a requiredcompressed state. Due to the extension action of the coil spring member14 c, the moving end part 14 b pushes against the circumferentialsurface of the disk-shaped insulating heat conductor 12.

A predetermined length of the wire-shaped shape memory alloy 11 isarranged so as to contact substantially half the region of thecircumferential surface of the disk-shaped insulating heat conductor 12(half circle curved surface). The two ends 11 a, 11 b of the wire-shapedshape memory alloy 11 are fastened to the base member 13 by screws 15 orother electrical terminals. The wire-shaped shape memory alloy 11, asshown in FIG. 3, is arranged inside of a groove 12 a which is formedwith for example a V-shaped cross-section in the circumferentialdirection of the circumferential surface of the disk-shaped insulatingheat conductor 12. Substantially the entire part of the wire-shapedshape memory alloy 11 is present inside the groove 12 a and contacts thegroove surfaces. In the usual extended state of the wire-shaped shapememory alloy 11, the disk-shaped insulating heat conductor 12 is pushedby the elastic mechanism 14 in the opposite direction of the arrow AL1,so substantially the entire region of the wire-shaped shape memory alloy11 is in a state firmly contacting the groove surfaces of the groove 12a.

As shown in FIGS. 2(A) and (B), the two ends 11 a and 11 b of thewire-shaped shape memory alloy 11 are connected through a switch 16 to apower source 17. The switch 16 and the power source 17 for an electricaldrive circuit for making the wire-shaped shape memory alloy 11 contract.The switch 16 is generally a semiconductor switch and is controlled toturn on/off by a pulse signal. As shown in FIG. 2(B), if the switch 16is turned on in the required short time, the wire-shaped shape memoryalloy 11 is instantaneously electrified. Due to this electrification,heat is instantaneously generated. As a result, the wire-shaped shapememory alloy 11 is instantaneously driven to contract. For this reason,as shown in FIG. 1 and FIG. 2(A), the disk-shaped insulating heatconductor 12 is instantaneously displaced in position in the directionof the arrow AL1 by exactly the distance “d” so as to compress the coilspring member 14 c against the pressing force of the elastic mechanism14. If intermittently electrifying the wire-shaped shape memory alloy11, the heat due to the electrification causes the wire-shaped shapememory alloy 11 to intermittently contract. The wire-shaped shape memoryalloy 11 contracts by about 4% with respect to its original length. Whenthe wire-shaped shape memory alloy 11 is no longer electrified, as shownin FIG. 4, the heat conduction action 18 by the disk-shaped insulatingheat conductor 12 causes the heat which was generated at the wire-shapedshape memory alloy 11 to rapidly disperse. As a result, the wire-shapedshape memory alloy 11 immediately returns to the original length state(extended state). In this way, in the wire-shaped shape memory alloy 11,contraction can be performed instantaneously in a relatively short timeinterval.

According to the impact drive type actuator 10 according to the firstembodiment which has the above constitution, the wire-shaped shapememory alloy 11 generates heat and contracts each time it isintermittently electrified and makes the disk-shaped insulating heatconductor 12 displace in position by exactly the distance “d” againstthe force of the elastic mechanism 14. After the end of theelectrification, the generated heat is dispersed by the heat conductionaction of the disk-shaped insulating heat conductor 12, so thewire-shaped shape memory alloy 11 quickly extends and the pushing actionof the elastic mechanism part 14 causes the disk-shaped insulating heatconductor 12 to return to its original position. In this way, the impactdrive type actuator 10 performs an impact drive operation.

In the disk-shaped insulating heat conductor 12, the planar shape of thesurface which contacts the wire-shaped shape memory alloy 11 is madedisk shaped for the following reason. The wire-shaped shape memory alloy11 is run through by current to contract resulting in movement of thedisk-shaped insulating heat conductor, but a shape where even in thestate after movement, the wire-shaped shape memory alloy 11 firmlycontacts the disk-shaped insulating heat conductor at most partsgenerally is a circular shape with a curve. In FIG. 2, (A) shows thestate before the wire-shaped shape memory alloy 11 contracts and (B) thestate after it contracts. In both states, the parts where thewire-shaped shape memory alloy 11 and the disk-shaped insulating heatconductor 12 contact are almost the same. If, for example, thedisk-shaped insulating heat conductor 12 were made a square shape formedby straight lines, movement of the disk-shaped insulating heat conductor12 would be accompanied with the wire-shaped shape memory alloy 11separating from it as a whole and the heat dispersion propertyremarkably deteriorating, so the result would no longer be suitable forthis application.

In the above, the insulating heat conductor 12 was explained aspreferably being disk shaped, but while not shown, it may also be aninsulating heat conductor which has a substantially circumferentialshape in only part. The point is that so long as the part which thewire-shaped shape memory alloy 11 contacts is substantiallycircumferential in shape, the inherent operation as an actuator becomescompletely the same.

Second Embodiment

Referring to FIG. 5 and FIG. 6, a second embodiment of the impact drivetype actuator according to the present invention will be explained. Inthe figures, 20 indicates an impact drive type actuator, 21 awire-shaped shape memory alloy, 22 for example, round rod shaped(columnar shape or pipe shape or other cross-sectional shape member)insulating heat conductors (below, referred to as representatively“round rod-shaped insulating heat conductors 22”), and 23A, 23B platemembers. Regarding the two plate members 23A and 23B, the bottom sideplate member 23A in FIG. 5 is a fixed side plate member, while the topside plate member 23B in the figure is the moving side plate member. Thetwo plate members 23A and 23B are arranged in parallel and facing eachother. The position of the plate member 23A does not change, but theplate member 23B is provided so as to be able to move in the directionof the arrow AL2 (up-down direction, thickness direction, or directionperpendicular to plate members 23A and 23B).

Between the two plate members 23A and 23B, a plurality of roundrod-shaped insulating heat conductors 22 are arranged in a parallelarrangement. The plurality of round rod-shaped insulating heatconductors 22 are divided into fixed side round rod-shaped insulatingheat conductors 22A and moving side round rod-shaped insulating heatconductors 22B.

On the fixed side plate member 23A, the plurality of fixed side roundrod-shaped insulating heat conductors 22A are arranged and fixed inparallel separated by predetermined distances. On the moving side platemember 23B, the plurality of moving side round rod-shaped insulatingheat conductors 22B are arranged and fixed in parallel separated bypredetermined distances. The fixed side and moving side round rod-shapedinsulating heat conductors 22A and 22B are, as shown in FIG. 6,alternately arranged. The numbers of the fixed side and moving sideround rod-shaped insulating heat conductors 22A and 22B aresubstantially equal. Between the fixed side round rod-shaped insulatingheat conductors 22A and the moving side round rod-shaped insulating heatconductors 22B, at least one wire-shaped shape memory alloy 21 isarranged so as to intersect the round rod-shaped insulating heatconductors in the long direction (preferably perpendicularly). In otherwords, the wire-shaped shape memory alloy 21 is arranged so as tocontact the plurality of mating projecting parts which are formed by thefixed side round rod-shaped insulating heat conductors 22A and themoving side round rod-shaped insulating heat conductors 22B between thetwo plate members 23A, 23B. The two ends of the wire-shaped shape memoryalloy 21 are fastened to the fixed side plate member 23A. The fixed sideround rod-shaped insulating heat conductors 22A are arranged at thefixed side plate member 23A side of the wire-shaped shape memory alloy21, while the moving side round rod-shaped insulating heat conductors22B are arranged at the moving side plate member 23B. The plate member23A and the plurality of round rod-shaped insulating heat conductors 22Aform the fixed side first component member 101, while the plate member23B and the plurality of round rod-shaped insulating heat conductors 22Bform the moving side second component member 102.

In the illustrated example which is shown in FIG. 5, the first componentmember 101 and the second component member 102 are comprised ofrespectively separate elements of the plate members 23A and 23B and thepluralities of round rod-shaped insulating heat conductors 22A and 22B,but these elements may be produced by integral shaping by cuttingaluminum or other metal materials and may be treated by alumite on theirsurfaces. Furthermore, the integrally shaped first and second componentmembers may be worked to be separated as projecting memberscorresponding to the round rod-shaped insulating heat conductors 22A,22B, then configured as the first and second component members. In thecase of this constitution, it is possible to omit the alumite treatmentof the surface for giving an insulation property. By separation in thisway, it is possible to secure an insulation property between adjoiningprojecting members and use the component member 101 and component member102 as a whole as insulating heat conductors.

The wire-shaped shape memory alloy 21 is intermittently electrified bythe switch 16 and the power source 17.

In the state where the wire-shaped shape memory alloy 21 is notelectrified, as shown in FIG. 6(A), the interval of the two platemembers 23A and 23B is in the state of h1. Between the two plate members23A, 23B, a coil spring member (not shown) is provided for tensing thetwo whereby the interval h1 is maintained. When the wire-shaped shapememory alloy 21 is electrified, as shown in FIG. 6(B), the wire-shapedshape memory alloy 21 contracts, the round rod-shaped insulating heatconductors 22B are made to displace upward against the coil springmember in the tensed state, and the interval between the two platemembers 23A and 23B is enlarged to give the interval h2.

According to the impact drive type actuator 20 according to the secondembodiment which has the above constitution, each time the wire-shapedshape memory alloy 21 is intermittently electrified, it generates heatand contracts and makes the moving side round rod-shaped insulating heatconductors 22B and plate member 23A displace in position so that theinterval between the two plate members 23A, 23B becomes larger. Afterfinishing electrification, the heat which is generated is dispersed bythe heat conduct ion act ion of the plurality of round rod-shapedinsulating heat conductors 22 (22A, 22B), so the wire-shaped shapememory alloy 21 quickly extends and, due to the pushing action of theelastic mechanism, the round rod-shaped insulating heat conductors 22Band plate member 23A return to their original positions. In this way,the impact drive type actuator 20 performs an impact drive operation inthe up-down direction.

Above, the explanation was given of the fact that if the wire-shapedshape memory alloy 21 is electrified, the interval between the firstcomponent member 101 and the second component member 102 becomes larger,but by changing it as follows in FIG. 6, the wire-shaped shape memoryalloy 21 can be electrified to make the interval contract small.

That is, while not shown, the wire of the wire-shaped shape memory alloy21 of FIG. 6 is laid from the left to form peak and valley shapes whichcontact the round rod-shaped insulating heat conductors 22A and 22B.This is changed to form valley and peak shapes from the left so as tocontact the round rod-shaped insulating heat conductors 22A and 22B.However, in this case, it is necessary to provide through holes throughwhich the wire-shaped shape memory alloy 21 passes in the plate members23A and 23B. In this case, opposite from the above, between the twoplate members 23A, 23B, coil spring members (not shown) are providedwhich expand the space between the two whereby a broader interval ismaintained before the wire-shaped shape memory alloy is electrified.

Further, in the above explanation, the explanation was given of the useof two wire-shaped shape memory alloys 21, but there may be just one ormay be more than two wire-shaped shape memory alloy parts 21 as well.Furthermore, the round rod-shaped insulating heat conductors 22 (22A,22B) need only contact the wire-shaped shape memory alloys 21 by theminimum lengths, so it is possible to reduce the width of the impactdrive type actuator 20 as a whole.

Further, in the above explanation, the members which are shown byreference numeral 22 were explained as round rod-shaped insulating heatconductors. However, the members 22 may also be heat conductors whichhave the property of carrying current at their surfaces, but areelectrically insulated from adjoining members (component members whichare formed by projecting members and correspond to “insulating heatconductors”). In this case, the cross-sectional shape of the insulatingheat conductors is not limited to a round, pipe, or other shape. Anyshape which forms projecting parts may be used. Furthermore, at thistime, for the surface material, copper or aluminum or other metal(conductive member) may be used. In this case, the wire-shaped shapememory alloy 21 is electrically short-circuited at the parts contactingthe members 22 (surface metal parts) so no heat is generated due toelectrification. In the wire-shaped shape memory alloy 21, the partwhich generates heat due to electrification is the part in the sectionbetween locations which adjoining two insulating heat conductorscontact. By adopting such a structure for the members 22, it is possibleto lower the equivalent electrical resistance, improve the heatconduction efficiency, and, furthermore, drive the impact drive typeactuator according to the present invention at a low voltage.

Third Embodiment

Referring to FIG. 7 to FIG. 11, a third embodiment of the impact drivetype actuator according to the present invention will be explained. InFIG. 7, 30 indicates an impact drive type actuator, 31 a wire-shapedshape memory alloy, and 32A and 32B rod-shaped (columnar, prismatic,pipe shape, etc.) insulating heat conductors (below, referred to as“rod-shaped insulating heat conductors 32A and 32B”). In the impactdrive type actuator 30 of the present embodiment, there are tworod-shaped insulating heat conductors 32A, 32B. One rod-shapedinsulating heat conductor 32A is fixed at its two ends to a base member33, while the other rod-shaped insulating heat conductor 32B is arrangedto be freely movable. The freely movable rod-shaped insulating heatconductor 32B is fixed at its two ends to support plates 34.Furthermore, the two support plates 34 at the two ends are connectedthrough coil spring members 35 in tensed states to fastening terminals36 on the base member 33. The two rod-shaped insulating heat conductors34A, 34B are arranged in parallel across a predetermined interval. Awire-shaped shape memory alloy 31 is wound a plurality of turns in aspiral in a ring shape around the two rod-shaped insulating heatconductors 34A, 34B so as to contact the outside circumferences. The twoends of the wire-shaped shape memory alloy 31 are connected toelectrical terminals 37 which are provided at the base member 33.Furthermore, between the two ends of the wire-shaped shape memory alloy31, a switch 16 and a power source 17 are connected.

The two rod-shaped insulating heat conductors 32A and 32B arerespectively basic component members for constituting the impact driveactuator 30 according to the present embodiment.

The freely movable rod-shaped insulating heat conductor 32B is tensed instate by the coil spring members 35, but since the wire-shaped shapememory alloy 31 is wound around it in a spiral manner, in the statewhere the wire-shaped shape memory alloy 31 is not electrified, it isarranged at a predetermined interval from the fixed rod-shapedinsulating heat conductor 32A as shown in FIG. 8(A). When the switch 16is turned on and the wire-shaped shape memory alloy 31 is electrified,the wire-shaped shape memory alloy 31 contracts, the rod-shapedinsulating heat conductor 32B is pulled in and displaces in thedirection of the arrow AL3, and, as shown in FIG. 8(B), the intervalbetween the two rod-shaped insulating heat conductors 32A and 32Bbecomes smaller by exactly the distance “d”.

In the above constitution of the embodiment which is shown in FIG. 7 andFIG. 8, the rod-shaped insulating heat conductors 32A, 32B have circularcross-section columnar shapes. The wound wire-shaped shape memory alloy31 is arranged so as to contact the circularly shaped curved outersurfaces of the rod-shaped insulating heat conductors 32A, 32B.Alternatively, the two rod-shaped insulating heat conductors 32A, 32B,as shown in FIG. 9, may be given flat surfaces at the facing surfaceparts and may be made substantially half circle shapes in cross-sectionso as to increase the contact area with the wire-shaped shape memoryalloy 31 while keeping the overall size small.

Further, regarding the method of winding the wire-shaped shape memoryalloy 31 around the two rod-shaped insulating heat conductors 32A, 32B,as shown in FIG. 10 and FIG. 11, a figure eight shape is also possible.In this case, it is possible to further increase the contact areabetween the wire-shaped shape memory alloy 31 and the rod-shapedinsulating heat conductors 32A, 32B, possible to further increase thelength of the wire-shaped shape memory alloy 31 as well, and possible tofurther increase the displacement caused.

While not shown, the two rod-shaped insulating heat conductors 32A, 32Bcan also function as a simple variable interval actuator since each timecurrent is passed, the wire-shaped shape memory alloy 31 contracts andthe interval between the two rods 32A, 32B is narrowed.

Fourth Embodiment

Referring to FIG. 12, a fourth embodiment of the impact drive typeactuator according to the present invention will be explained. In FIG.12, 50 indicates an impact drive type actuator. This impact drive typeactuator 50 functions as a high speed response rotation brake device. Asone example of application, when a manually operated volume dial orrotary switch etc. is turned, the rotation brake action of the impactdrive gives a “click” feeling. Reference numeral 51 is a wire-shapedshape memory alloy, while 52 is a rotor shaped insulating heat conductorwhich has a shaft 53 at its center axis (below, referred to as “rotorinsulating heat conductor 52”). The top end of the shaft 53 is furtherextended and connected to the rotational drive part, but in the exampleillustrated in FIG. 12, the extended part at the top end of the shaft 53is omitted. In the impact drive type actuator 50 of the presentembodiment, the wire-shaped shape memory alloy 51 is wound bysubstantially one turn around the outer circumferential surface of therotor insulating heat conductor 52. The two ends of the wire-shapedshape memory alloy 51 are fixed to fastening terminals 54A, 54B on abase member 54. Further, between the two ends of the wire-shaped shapememory alloy 51, a switch 16 and power source 17 are connected by aserial connection.

The rotor insulating heat conductor 52 is structured so as to be drivento rotate as shown by the arrow AL4 by the shaft 53 based on an externaldrive force. Therefore, when in a usual state where the wire-shapedshape memory alloy 51 is not electrified, the wire-shaped shape memoryalloy 51 contacts the outer circumferential surface of the rotorinsulating heat conductor 52, but does not strongly contact it.Therefore, the rotor insulating heat conductor 52 is in a state where itdoes not receive a brake action and freely rotates without constraint.If electrifying the wire-shaped shape memory alloy 52, the wire-shapedshape memory alloy 52 instantaneously contracts and strongly contactsthe outer circumferential surface of the rotor insulating heat conductor52 to tighten against the rotor insulating heat conductor 52. As aresult, the rotating state rotor insulating heat conductor 52 issubjected to a strong brae force. When electrification ends, the heatwhich is generated at the wire-shaped shape memory alloy 51 is dispersedthrough the rotor insulating heat conductor 52. As a result, thewire-shaped shape memory alloy 51 returns to its original length, thetightening force ends, and the brake action is lifted.

According to the impact drive type actuator 50 according to the fourthembodiment which has this constitution, the rotor insulating heatconductor 52 which rotates due to the rotational drive force which isgiven from the outside through the shaft 53 is tightened against by theelectrification and contraction of the wire-shaped shape memory alloy 51which is wound around its outer circumferential surface and therebysubjected to a brake action. The intermittent instantaneous brake actionon the rotor insulating heat conductor 52 based on the wire-shaped shapememory alloy 51 gives an impact to the shaft 53 and can give a “click”feeling to the operator who is turning the shaft 53.

Fifth Embodiment

Referring to FIG. 13 and FIG. 14, a fifth embodiment of the impact drivetype actuator according to the present invention will be explained. InFIG. 13, 60 is an impact drive type actuator. Due to this impact drivetype actuator 60, a motor is realized which turns in a direction such asfor example shown by the arrow AL5. The impact drive type actuator 60 isconfigured by a wire-shaped shape memory alloy 61 and an insulating heatconductor 62 which forms a for example hollow cylindrical shaped rotor(below, referred to as a “rotor insulating heat conductor 62”). Therotor insulating heat conductor 62 is provided so as to be able to beturned freely on the base member 63 by a rotary support mechanism 62A.The rotor insulating heat conductor 62 has a predetermined length in theaxial direction and is formed with a spiral thread 62B at the surface ofits outer circumference. The wire-shaped shape memory alloy 61 isarranged wound for example by one turn in contact with the groove alongthe thread groove of the outer circumferential surface of the rotorinsulating heat conductor 62. One end of the wire-shaped shape memoryalloy 61 is fastened to a fastening terminal 64A of the base member 63,while the other end is fastened through an extended coil spring member65 to a fastening terminal 64B. Further, between the two ends of thewire-shaped shape memory alloy 61, a pulse drive device 66 iselectrically connected. The wire-shaped shape memory alloy 61 iscyclically supplied with pulse current. FIG. 14 shows an example of acyclic pulse drive current which the pulse drive device 66 outputs.

In this impact drive type actuator 60, when pulse current is given fromthe pulse drive device 66, the wire-shaped shape memory alloy 61 in theextended state generates heat by electrification by the pulse currentand disperses the heat after that whereby it cyclically repeats acontract ion action. If the wire-shaped shape memory alloy 61 contracts,it tightens against the outer circumferential surface of the rotorinsulating heat conductor 62, the coil spring member 65 is pulled long,and therefore the rotor insulating heat conductor 62 turns in thedirection of the arrow AL5 by exactly a predetermined angle. When notelectrified, the heat of the wire-shaped shape memory alloy 61 isdispersed through the rotor insulating heat conductor 62 and the alloyextends in length. At this time, friction between the rotor insulatingheat conductor 62 and the wire-shaped shape memory alloy 61 becomessmaller and the coil spring member 65 pulls back the wire-shaped shapememory alloy 61 to its original position. A predetermined angle ofrotational operation of the rotor insulating heat conductor 62 isperformed each time a pulse current is applied. As a result, the rotorinsulating heat conductor 62 rotates in the direction of the arrow AL5.Note that when the wire-shaped shape memory alloy 61 is in the extendedstate, it contacts the outer surface of the rotor insulating heatconductor 62 in a loose state.

In the impact drive type actuator 60, along with rotation of the rotorinsulating heat conductor 62 at the rotary support mechanism 62A, therotor insulating heat conductor 62 moves in the axial direction.According to the impact drive type actuator 60 which has such amechanism, for example, by attaching a camera lens inside of the hollowpart of the rotor insulating heat conductor 62, the assembly can beconfigured as a focus adjustment mechanism of a camera lens.

In application as a focus adjustment mechanism of a camera lens, due tothe spiral shaped thread 62B, rotation of the rotor insulating heatconductor 62 enables the insulating heat conductor 62 to advance andretract for a linear motion function even without another holdingmechanism etc. With this constitution, it is possible to simply shortenthe length of the optical axis in the camera lens direction.

Sixth Embodiment

Referring to FIG. 15 and FIG. 16, a sixth embodiment of the impact drivetype actuator according to the present invention will be explained. Thissixth embodiment is a modification of the fifth embodiment. That is, inthe constitution of the impact drive type actuator 60 according to thefifth embodiment, the motor turned in a single direction, but in theconstitution of the impact drive type actuator 60-1 according to thepresent embodiment, it is possible to realize a motor which can turn inthe opposition direction as well. That is, as shown in FIG. 15,regarding the rotational operation of the rotor insulating heatconductor 61, this is configured to rotate in the rotational directionwhich is opposite to the rotational direction which is shown by thearrow AL5 (clockwise direction), that is, which is shown by the arrowAL6 (counterclockwise direction).

In this constitution, in addition to the constitution which wasexplained by FIG. 13, another wire-shaped shape memory alloy 71 is woundin the thread groove of the outer circumferential surface of the rotorinsulating heat conductor 62. The winding direction of the wire-shapedshape memory alloy 71 is a winding direction which is opposite to theabove-mentioned wire-shaped shape memory alloy 61. Further, the threadgroove in which the wire-shaped shape memory alloy 71 is wound isseparate from the thread groove in which the wire-shaped shape memoryalloy 61 is wound, that is, the two are set so as not to become thesame. In other words, the two wire-shaped shape memory alloys 61, 71 arearranged in thread grooves so as not to contact each other.

One end part of the wire-shaped shape memory alloy 71 is fastened to thefastening terminal 72A of the base member 63, while the other end partis fastened to the fastening terminal 72B through the extended coilspring member 73. Further, between the two ends of the wire-shaped shapememory alloy 71, another pulse drive device (not shown) is electricallyconnected whereby the wire-shaped shape memory alloy 71 is cyclicallysupplied with pulse current. The other pulse drive device is a devicesimilar to the above-mentioned pulse drive device 66. By the other pulsedrive device outputting a pulse signal, the wire-shaped shape memoryalloy 71 is cyclically made to contract and the rotor insulating heatconductor 62 is made to rotate in the direction of the arrow AL6.

FIG. 16 shows the rotational operation of the rotor insulating heatconductor 62, that is, rotational operation in the direction of thearrow AL6 (counterclockwise direction) (A) and rotational operation inthe direction of the arrow AL5 (clockwise direction) (B). In the tworotational operations (A), (B), pulse drive devices 66, 74 comprised ofa switch 16 and power source 17 are used to supply pulse current. Whenthe switch 16 is turned off, pulse current is run. Due to this, thewire-shaped shape memory alloys 61, 71 change in state from the extendedstate (1) to the contracted state (2) and again to the extended state(3) as a result of which rotational drive is performed. When thewire-shaped shape memory alloys 61, 71 are in the extended state, thewire-shaped shape memory alloys 61, 71 gently contact the outercircumferential surface of the rotor insulating heat conductor 62. Whenthe wire-shaped shape memory alloys 61, 71 in the extended state areelectrified and become the contracted state, the wire-shaped shapememory alloys 61, 71 tighten against the outer circumferential surfaceof the rotor insulating heat conductor 62, the coil spring members 65,73 extend, and a predetermined angle of rotation occurs in therespectively set directions. By repeating the supply of pulse current,the extended state (1), the contracted state (2), and the extended state(3) are repeated and rotation is performed. Either of the contractionoperation by the wire-shaped shape memory alloy 61 and the contractionoperation by the wire-shaped shape memory alloy 71 is selectivelyperformed.

FIG. 17 shows the engagement relationship between the rotor insulatingheat conductor 62 and the wire-shaped shape memory alloy 61 (or 71) inthe impact drive type actuators 60, 60-1 which function as rotarymotors. The wire-shaped shape memory alloy 61 (or 71) is arranged in thethread grooves 62B-1 of the spiral shaped thread 62B which is formed atthe outer circumferential surface of the rotor insulating heat conductor62. The rotor insulating heat conductor 62 is formed by an insulatingmaterial. For example, as shown in FIG. 17, the wire-shaped shape memoryalloy 61 (or 71) is present inside different thread grooves 62B-1 andthere is a thread turn 62B-2 between the two, so the wire-shaped shapememory alloys 61 (or 71) are separated and will never short-circuit instate. The wire-shaped shape memory alloy 61 (or 71) firmly contacts therotor insulating heat conductor 62 inside of the thread grooves 62B-1,so efficient heat dispersion is possible. The wire-shaped shape memoryalloy 61 acting in the right direction (AL5) and the wire-shaped shapememory alloy 71 acting in the left direction (AL6) are wound severalturns apart so that the wires do not hit each other since the spiralthread 62B of the rotor insulating heat conductor 62 is cut with a largenumber of thread turns.

Seventh Embodiment

Referring to FIG. 18 and FIG. 19, a seventh embodiment of the impactdrive type actuator according to the present invention will beexplained. In FIG. 18, 80 indicates an impact drive type actuator. Thisimpact drive type actuator 80 is for example a linear movement typeactuator in which a moving member moves in the direction such as shownby the arrow AL7. The impact drive type actuator 80 is comprised of awire-shaped shape memory alloy 81 and two rectangular plate-shapedinsulating heat conductors 82A, 82B which are arranged in parallel andoverlaid (below, referred to as “the plate-shaped insulating heatconductors 82A, 82B”). The bottom side plate-shaped insulating heatconductor 82A is fixed in place and is used as a fixed member. The topside plate-shaped insulating heat conductor 82B has one end 82B-1connected through a tensed coil spring member 84 to a fastening terminalpart 83 and the other end 82B-2 as a free end. The plate-shapedinsulating heat conductor 82B is arranged so as to be able to move inthe long direction of the plate-shaped insulating heat conductor 82A(direction of the arrow AL7) in the state substantially overlaying thefixed plate-shaped insulating heat conductor 82A. The wire-shaped shapememory alloy 81, as shown in FIG. 19, is arranged in the space betweenthe two overlaid plate-shaped insulating heat conductors 82A, 82B and isconnected to one end 82A-1 of the plate-shaped insulating heat conductor82A and one end 82B-1 of the plate-shaped insulating heat conductor 82B.In the usual state not electrified, the wire-shaped shape memory alloy81 is in the extended state. Therefore, the wire-shaped shape memoryalloy 81 which is connected to the one end 82A-1 of the plate-shapedinsulating heat conductor 82A and the one end 82B-1 of the plate-shapedinsulating heat conductor 828 is in the extended state since the end82B-1 is pulled by the coil spring member 84. If the wire-shaped shapememory alloy 11 is intermittently electrified, the wire-shaped shapememory alloy 11 contracts and the top side plate-shaped insulating heatconductor 82B instantaneously moves in the direction of the arrow AL7against the action of the coil spring member 84. Between the two ends ofthe wire-shaped shape memory alloy 11, a drive circuit is electricallyconnected. Reference numeral 85 indicates electrical wiring forelectrification use. The top side plate-shaped insulating heat conductor82B functions as a moving member.

The impact drive type actuator 80, as explained below, places the movingmember on the moving member constituted by the plate-shaped insulatingheat conductor 82B, so is utilized as a linear movement type actuatorwhich makes the moving member move.

Eighth Embodiment

Referring to FIG. 20 and FIG. 21, an eighth embodiment of the impactdrive type actuator according to the present invention will beexplained. This embodiment is configured based on the impact drive typeactuator enabling linear movement of a moving member which was explainedin FIG. 18. By placing the moving member 86 on the moving memberconstituted by the plate-shaped insulating heat conductor 82B, themoving member 86 is made to move linearly. The other parts of theconstitution are the same as the constitution which is explained by FIG.18. In the above constitution which is shown in FIG. 20, componentswhich are the same as components which are shown in FIG. 18 are assignedthe same reference numerals.

The box-shaped moving member 86 which is placed on the moving memberconstituted by the plate-shaped insulating heat conductor 82B is placedconstrained in movement direction so as to be able to move linearly onlyalong the long direction of the plate-shaped insulating heat conductor82B. Between the top surface of the plate-shaped insulating heatconductor 82B and the bottom surface of the moving member 86, a frictionpart 87 is formed.

Next, referring to FIG. 21, the linear type movement of the movingmember based on the impact drive type actuator 80 according to thepresent embodiment will be explained.

The state of FIG. 21(A) is the state where, in the drive circuitconstituted by the switch 16 and the power source 17, the switch 16 isoff in state. Therefore, the upper side plate-shaped insulating heatconductor 82B is pulled by the coil spring member 84 and the wire-shapedshape memory alloy 81 extends in state.

In the state of FIG. 21(B), the switch 16 is rapidly turned on and thewire-shaped shape memory alloy 81 is electrified in a pulse like mannerwhereby the wire-shaped shape memory alloy 11 instantaneously contracts.As a result, the plate-shaped insulating heat conductor 82Binstantaneously displaces in the direction of the arrow AL7 by exactly Pagainst the coil spring member 84. Even if the plate-shaped insulatingheat conductor 82B displaces, the moving member 86 on the plate-shapedinsulating heat conductor 82B slides on the friction part 87 due toinertia, so the moving member 86 is not displaced and the moving member86 remains at its position.

If, after that, in the state of FIG. 21(C), the switch 16 is turned offand the alloy is no longer electrified, the wire-shaped shape memoryalloy 81 disperses its heat and slowly returns to its original length(extended state). The position of the plate-shaped insulating heatconductor 82B also is pulled by friction by the coil spring member 84 toreturn to its original position. As a result, the position of the movingmember 86 also changes along with movement of the plate-shapedinsulating heat conductor 82B. At this time, the moving member 86finally moves by exactly the distance “d” in the left direction in thefigure.

If cyclically electrifying the wire-shaped shape memory alloy to repeatthis change of state, it is possible to make the moving member 86 movelinearly in the left direction in the figure.

According to the impact drive type actuator 80 for linear movement useaccording to the present embodiment, it is possible to increase theamount of movement per operation compared with a linear actuator using apiezoelectric device, possible to greatly lower the drive frequency, andpossible to realize a linear movement type actuator by a low cost,simple drive circuit constitution.

Next, the drive circuit for contraction and extension of theabove-mentioned wire-shaped shape memory alloys 11, 21, 31, 51, 61, 71,and 81 (below, referred to as “the wire-shaped shape memory alloy 11etc.”) will be explained with reference to FIG. 22 and FIG. 23. Thewire-shaped shape memory alloy 11 etc. intermittently contracts based onthe pulse-like electrification given from the drive circuit 41. Thedrive circuit 41 is comprised of a DC/DC converter 42, battery 43,charging resistor 44, and discharge use capacitor 45. The drive circuit41 converts the DC voltage which is supplied by the battery 43 at theDC/DC converter 42 to generate, for example, a boosted predetermined DCvoltage. The drive circuit 41 is a specific circuit configuration of thepower source 17. Reference numeral 46 indicates the output end of thedrive circuit 41. At the output end 46, as a load, one end of thewire-shaped shape memory alloy 11 etc. is connected. At the other end ofthe wire-shaped shape memory alloy 11 etc., a switching transistor 47 isconnected with the ground. The switch transistor 47 corresponds to theabove-mentioned switch 16. The switching transistor 47 is supplied witha pulse signal at the control terminal 47 a which is connected to thebase. By the switching transistor 47 being supplied with the controlsignal, the switching transistor 47 instantaneously turns on and currentIm flows, whereby the wire-shaped shape memory alloy 11 etc. isinstantaneously electrified. By the base of the switching transistor 47being supplied with the pulse signal, the wire-shaped shape memory alloy11 etc. is intermittently supplied with current each time.

FIG. 23 shows the change characteristics (A) of the voltage of thedischarge use capacitor 45 at the drive circuit 41, the changecharacteristics (B) of the load current Im, and the changecharacteristics (C) of the length of the wire-shaped shape memory alloy11. In the change characteristics (C) of the length of the wire-shapedshape memory alloy 11 etc., the range 48 becomes the range at the timeof heating while the range 49 becomes the range at the time of cooling.To maintain the cooling time at the wire-shaped shape memory alloy 11long, the electrification time of the wire-shaped shape memory alloy 11etc. is made short and the off time is made long. Further, to shortenthe electrification time as much as possible, the drive circuit 41 usesa high voltage (for example 20V) and a large current (for example, thepeak current 2A) as output to drive the wire-shaped shape memory alloy11. Note that, in accordance with the conditions which are sought in thedesign of the impact drive type actuator, the drive circuit 41 may beconfigured so as to directly drive the wire-shaped shape memory alloy 11etc. by pulse-like electrification from the input voltage of the batterywhen the battery 43 has a current supply ability. In this case, theDC/DC converter 42, charging resistor 44, and discharge use capacitor 45become unnecessary and the drive circuit 41 can be simplified.

To improve the response speed of the wire-shaped shape memory alloy 11etc. to make it intermittently contract or extend, it is necessary toincrease the cooling time as much as possible. For this reason, toshorten the electrification time in such a limited time period, it isnecessary to shorten the pulse duty (electrification time/cycle) andincrease the wave height. For this reason, a voltage greater than thevoltage of the battery 43 becomes necessary, so a DC/DC converter 41 isused for boosting the voltage. Further, the discharge use capacitor 45is charged to a high voltage and the switching transistor 47 turned ONso as to make the charge which is stored in the discharge use capacitor45 be discharged all at once in the form of current. This time is thedischarge time Tr. The resistance value of the wire-shaped shape memoryalloy 11 etc. is low, so the current Im instantaneously flows.

The current Im flows through the wire-shaped shape memory alloy 11 etc.instantaneously whereby the wire-shaped shape memory alloy itself isheated and the wire-shaped shape memory alloy 11 etc. contact so as tostrongly contact the insulating heat conductor. The current isinstantaneous, so when the wire-shaped shape memory alloy 11 etc. abutsagainst the insulating heat conductor, the current flowing becomessubstantially zero. For this reason, even if the insulating property ofthe insulating heat conductor deteriorates, no short-circuit state willresult and no large current will continue to flow, so the circuitbecomes safe.

Above, a wire-shaped shape memory alloy was explained, but thecross-section need not be round. The alloy may also be made one with asquare cross-sectional shape.

The configurations, shapes, sizes, and relative layouts explained in theabove embodiments are only shown schematically to an extent enabling thepresent invention to be understood and worked. Further, the numericalvalues and compositions (materials) of the constitutions etc. are onlyillustrations. Therefore, the present invention is not limited to theembodiments explained above and can be changed in various ways so longas not departing from the scope of the technical ideas shown in theclaims.

INDUSTRIAL APPLICABILITY

The impact drive type actuator according to the present invention isconfigured utilizing the extension and contraction action of awire-shaped shape memory alloy. After being electrified to generateheat, it utilizes the heat dispersion action of a disk-shaped insulatingheat conductor etc. to lower the temperature so as to improve theresponse. This is utilized as a highly practical impact drive typeactuator. Furthermore, it is used as the drive mechanism of a rotarymotor or a linear motor.

EXPLANATION OF REFERENCES

-   -   10 impact drive type actuator    -   11 wire-shaped shape memory alloy    -   12 disk-shaped insulating heat conductor    -   13 base member    -   14 elastic mechanism    -   14 c coil spring member    -   15 screw    -   16 switch    -   17 power source    -   20 impact drive type actuator    -   21 wire-shaped shape memory alloy    -   22 round rod-shaped insulating heat conductor    -   22A fixed side round rod-shaped insulating heat conductor    -   22B moving side round rod-shaped insulating heat conductor    -   23A plate member    -   23B plate member    -   30 impact drive type actuator    -   31 wire-shaped shape memory alloy    -   32A rod-shaped insulating heat conductor    -   32B rod-shaped insulating heat conductor    -   33 base member    -   34 support plate    -   35 coil spring member    -   36 fastening terminal    -   37 electric terminal    -   41 drive circuit    -   42 DC/DC converter    -   44 charging resistor    -   45 discharge capacitor    -   47 switching transistor    -   50 impact drive type actuator    -   51 wire-shaped shape memory alloy    -   52 rotor insulating heat conductor    -   53 shaft    -   54 base member    -   60 impact drive type actuator    -   60-1 impact drive type actuator    -   61 wire-shaped shape memory alloy    -   62 rotor insulating heat conductor    -   63 base member    -   65 coil spring member    -   66 pulse drive device    -   71 wire-shaped shape memory alloy    -   73 coil spring member    -   80 impact drive type actuator    -   81 wire-shaped shape memory alloy    -   82A plate-shaped insulating heat conductor    -   82B plate-shaped insulating heat conductor    -   84 coil spring member    -   86 moving member    -   101 first component member    -   102 second component member

The invention claimed is:
 1. An impact drive type actuator comprising: awire-shaped shape memory alloy (11, 21, 31) which contracts upon beingelectrified and heated, an insulating heat conductor (12, 22, 22A, 32A,32B) which contacts said wire-shaped shape memory alloy, is pushed inone direction by said contracted wire-shaped shape memory alloy andreleases the heat which is generated at said wire-shaped shape memoryalloy, a drive circuit (16, 17, 41, 66) which instantaneouslyelectrifies said wire-shaped shape memory alloy (71, 81) to make saidwire-shaped shape memory alloy contract, and wherein said wire-shapedshape memory alloy makes said insulating heat conductor displacetranslationally by a predetermined distance from a first position whensaid wire-shaped shape memory alloy is electrified and contracts, and apushing operation between said wire-shaped shape memory alloy and saidinsulating heat conductor makes said wire-shaped shape memory alloyextend by instantaneous dispersion (18) of heat which is stored by beingelectrified and thereby said insulating heat conductor is made todisplace translationally to said first position.
 2. The impact drivetype actuator as set forth in claim 1, wherein: said insulating heatconductor at least partially has a substantially circumferential shape,said wire-shaped shape memory alloy is arranged so as to contact thecircumferential surface of said insulating heat conductor, and saidwire-shaped shape memory alloy makes said insulating heat conductordisplace translationally in position when it is electrified andcontracts.
 3. The impact drive type actuator as set forth in claim 2,wherein said circumferential surface of said insulating heat conductoris formed with a groove (12 a), and said wire-shaped shape memory alloyis arranged in said groove.
 4. The impact drive type actuator as setforth in claim 1, wherein said insulating heat conductor is comprised oftwo component members (101, 102) which face each other substantially inparallel and have pluralities of mating projecting parts (22A, 22B),said wire-shaped shape memory alloy is arranged between said twocomponent members so as to contact said mating projecting parts, andsaid wire-shaped shape memory alloy makes displacement so as to cause aninterval between said two component members to enlarge when it iselectrified and contracts.
 5. The impact drive type actuator as setforth in claim 1, wherein said insulating heat conductor is comprised oftwo component members (32A, 32B) which face each other substantially inparallel and have substantially rod shapes or pipe shapes, saidwire-shaped shape memory alloy is spirally wound around said twocomponent members so as to contact their circumferences, and saidwire-shaped shape memory alloy makes said two component members displaceso as to reduce the interval between them when it is electrified andcontracts.
 6. The impact drive type actuator as set forth in claim 5,wherein said wire-shaped shape memory alloy is wound in a ring shape ora figure eight shape.
 7. The impact drive type actuator as set forth inclaim 5, wherein said two component members of said insulating heatconductor are respectively comprised so that at least the outer surfaceswhich contact said wire-shaped shape memory alloy are curved so thattheir cross-sections include substantially half circles.
 8. The impactdrive type actuator as set forth in claim 1, wherein said drive circuitis comprised of a booster circuit (42) which converts input voltage to ahigh voltage, a capacitor (45) which is charged by that output voltage,and a switching device (47) which is connected in series with saidwire-shaped shape memory alloy from said capacitor and instantaneouslyruns current to said wire-shaped shape memory alloy.
 9. The impact drivetype actuator as set forth in claim 1, wherein said insulating heatconductor at least at a surface part which contacts the wire-shapedshape memory alloy is constituted by a material selected from the groupconsisting of alumina and aluminum nitride.
 10. The impact drive typeactuator as set forth in claim 1 wherein said insulating heat conductoris comprised of two component members which face each othersubstantially in parallel and which are provided with pluralities ofprojecting members, at each of said two component members, saidplurality of projecting members are separated, said pluralities ofprojecting members are comprised of conductive members, and between saidtwo component members, said wire-shaped shape memory alloy is arrangedso as to contact parts comprised of said conductive members of saidprojecting members, and said wire-shaped shape memory alloy changes theinterval of said two component members when it is electrified andcontracts.